1. Field of the Invention
This invention relates generally to systems for winding continuous webs of sheet material, such as plastic film, onto cores to form individual rolls. More particularly, this invention relates to apparatus and methods for unloading wound production rolls from the shaft of a winder, such as a swing-out winder, and for loading or reloading the winder shaft with empty cores in preparation for further winding.
2. Description of the Related Art
A roll of sheet material is typically formed by winding a continuous web of sheet material onto a core, typically in a winding machine that is capable of winding a plurality of cores simultaneously. In this regard, automatic winding machines employing one or more swing-out shafts may be used. Winding machines having shafts mounted on a rotating turret are also typically employed. One such machine is known as a cantilevered winding machine. In the operation of a typical cantilevered winding machine, two swing-out winding shafts are typically employed. The use of two winding shafts allows plastic film to be wound on a plurality of cores on a first shaft at the same time wound rolls on a second shaft are unloaded and replaced with cores. When the cores on the first shaft have been fully wound with sheet material, the turret is rotated so that the cores on the second shaft are placed in position within the winding machine for winding, and so that the wound rolls on the first shaft may be removed and replaced with cores. This process is typically repeated over and over during the winding operation.
In most cases, a winder is capable of winding rolls of sheet material faster than the rolls may be replaced with cores. In typical winding operations, wound production rolls are typically unloaded from a winding shaft by hand, and cores are typically loaded onto a winding shaft by hand. Operations employing hand loading and unloading usually require at least about one minute and 15 seconds or more, depending on the number of rolls being wound, to prepare a winding shaft for further winding by replacing wound rolls with cores. However, a typical winder is capable of winding a set of cores with about 1200 feet to about 1800 feet of sheet material in less than about one minute. Therefore, the efficiency of a typical film winding operation is usually dependent on the time required for replacing wound rolls with cores on a winding shaft. Furthermore, typical conventional winding operations require more than one person, typically three people, to accomplish core loading, winding, and roll unloading.